I don't see what the big deal is. You take exactly the same risk when you download a mod for, say Half-Life, or when you download anything executable for that matter (e.g. a utility from download.com).
It concerns me that a lot of your suggestions may limit unscrupulous users, yet they will also limit those with a legitimate use for a particular function.
Also, btw, a lot of virus scanners can detect "virus-like activity" and flag up a message to the user. I'm not sure how effective this is though.